Elevator door control



NOV. 27, 1934. 5, Lu 1,982,442

ELEVATOR DOOR CONTROL Filed July 23, 1934 4 Sheets-Sheet 1 INVENTOR' l f BY ATTORNEY Nov. 27, 1934. s. LUBKIN 1,982,442

- ELEVATOR DOOR CONTROL Filed July 23, 1934 4 Sheets-Sheet 3 mi 5 E I BY W ATTORNEY Patented Nov; 27, 1934 PATENT OFFICE ELEVATOR DOOR CONTROL Samuel Lubkin, Brooklyn, N. Y., assignor to Otis Elevator Company, New York, N. Y., a corporation of New Jersey Application July 23, 1934, serial No. 736,548

20 Claims.

This invention relates to equipment for controlling car and hatchway doors in elevator installations.

In elevator installations the car door and/or 3 the hatchway doors are frequently caused to open or to close, or to both open and close, by means of appropriate power devices, such as electric motors, pneumatic engines, or springs, operatively connected to such doors.

One feature of the invention is the provision of a safety control over the door actuating equipment for elevator car and hatchway doors so that, in the event a person or any portion of his body, 'or in the event some inanimate object, is in the path of the door while the door is open, the door actuating equipment is rendered ineifective to close the door.

A second feature of the invention resides in providing that such safety control is effective, in

the event the car or hatchway door, in closing, nears an obstruction such as a person or a portion of his body or an inanimate object, to automatically stop the door before it can hit or cause injury to such person or object.

l A third feature of the invention resides in attaining such safety control of the elevator car and hatchway doors with a minimum of equipment and a maximum of effectiveness.

A fourth feature of the invention resides in providing a safety control for the elevator car and hatchway doors in which equipment therefor carried on the car is eifective to provide protection to a person who is, or any portion of whom is, or to an inanimate object which is, in the path of either the car door or the hatchway door, or in the zone between the car door and the hatchway door.

, A fifth feature of the invention resides in providing a safety control for elevator car and hatch- 40 way doors which is not influenced by the accumulation of dust, grease or dirt on exposed parts,

which is sturdy and comparatively mune from danger of breakage, and which does not employ unsightly instrumentalities.

A sixth feature of the invention resides in utilizing the electrical characteristics'of a body, animate or inanimate, when it is in the entranceway to the elevator car, for altering the behavior of an electrical instrumentality and thereby to control the operationof the door or doors for such entranceway in such manner as to bring the door or doors, when closing, to a stop before they can strike such body.

A seventh feature of the invention resides in providing an electrostatic field in the entranceway to the elevator car with provision that alteration of such electrostatic field-as by the presence therein of an animate or inanimate body, controls the operation of the door or doors to such entranceway in such manner as to prevent the 69 door or doors causing injury to such body.

An eighth feature of the invention is the provision of means for preventing alterations of the electrostatic field due to extraneous causes, such as the alteration of the electrostatic field attendant upon movement of the elevator doors, from effecting any control of the elevator doors.

- Other features will become apparent from the specification taken in conjunction with the accompanying drawings and the subjoined claims.

In the drawings:

Figure 1 is a front elevation of an elevator car and a'portion of an associated hatchway door, illustrating one form of the invention;

Figure 2 is a sectional view of the front portion of the elevator car taken along the line 2-2of Figure 1, with the section extended to include the associated hatchway opening and hatchway door;

Figure 3 is an enlarged sectional view of the car door and capacity plates secured thereto, taken along the line 3-3 of Figure 1;

Figure 4 is an enlarged view, in vertical section, of the compensating condenser illustrated in Figure 1;

Figure 5 is a schematic wiring diagram for the form of the invention illustrated in Figure 1;

Figure 6 is a set of curves employed in explaining the'invention;

Figure 7 is a front elevation of an elevator car illustrating another form of the invention;

Figure 8 is a side elevation of the elevator car illustrated in Figure 7, and showing, in addition, the hatchway door for an opening opposite which the elevator car is at rest;

Figure 9 is an enlarged sectional view taken along the line 9-9 of Figure 8; and

Figure 10 is a schematic wiring diagram for the form of the invention illustrated in Figure '7.

As an aid in the rapid understanding of the invention, all equipment in all the figures has been shown in the positions taken by such equipment when the elevator car is stationary opposite a hatchway opening, when the car and hatchway doors are stationary in open position, when no personor other obstruction is in the entranceway to the elevator car, and, for the wiring diagrams, when the source of power is disconnected therefrom.

The invention involves employing the electrical characteristics of a human being or other body, no

animateor inanimate, to'efiect a change in the behavior of an electrical instrumentality while such human being or other body is in the entranceway to the elevator car. Appropriate devices are'made responsive to the change of behavior of such instrumentality so that the door or doors to such entranceway cannot injure the human being while he, or such other body while it, is in such entranceway. In the two embodiments of the invention'herein described, the electrical characteristics of the human being or other body are utilized to effect a change in an electrostatic field that is established in the entranceway to the elevator car. In these two embodiments the electrostatic field is produced by impressing a voltage across two plates insulated from each other and carried on the hatchway side of the car door near the front edge thereof. Preferably, the two plates are so shaped and mounted that the electrostatic field produced thereby extends in advance of the front edge of the car door, extends laterally so as to include the zone between the car door and hatchway door, and extends in advance of the front edge of the hatchway door. Such a field is obtainable since dispersion is a characteristic of electrostatic fields, and since by appropriate design and construction of the plates creating an electrostatic field, there is obtained a measure of control over the physical form of such electrostatic field.

In the two embodiments of the invention illustrated, the change effected in the electrostatic field due to the presence of a human being or other body therein is utilized by utilizing means responsive to the resulting change in the net capacity in a circuit in which the electrostatic-fieldproducing plates are connected. Such means, in the embodiments illustrated, is a tuned circuit, one element of which is the capacity that is subject to change when a human being or other body is in the electrostatic field thereof. With such an arrangement, the resonant characteristics of such a tuned circuit are subject to control by the presence of a human being or other body in the entranceway to the elevator car.

In utilizing such a tuned circuit for controlling the doors for such elevator entranceway, it is desired to have it regulate the magnitude of a high frequency voltage impressed upon a unidirection current-transmitter and amplifier, such as a triode vacuum tube or other suitable electronic device. The tuned circuit is inductively fed with high frequency oscillations of a given frequency, with the net capacity in such tuned,

circuit, when no human being or other body is in the entranceway, of such a value as to have the tuned circuit in resonance with the high frequency oscillations inductively impressed upon it. The voltage across the inductance of the tuned circuit is thus a maximum, so that the output current from such electronic device is a maximum.

The tuned circuit is detuned from resonance with the high frequency oscillations inductively impressed upon itwhen the electrostatic field in the elevator entranceway is altered by the presence of a human being or other body therein. The voltage across the inductance of the tuned circuit is then of a value lower thanthc aforementioned maximum, and therefore the output current from the electronic device is of a value lower than its maximum. ,In the embodiments of the invention illustrated, the percentage decrease in the value of the output cur rent of the electronic device, when a body is in the entranceway, is made considerably greater than the percentage decrease in the value of the voltage across the inductance in the tuned circuit by utilizing for the electronic device an appropriate triode vacuum tube and operating it with a large negative grid bias.

, A relay is placed in the output circuit of the electronic device and is of such sensitivity that it responds to any material decrease in the output current of such device below the maximum output current thereof. Such relay is therefore operated when a human being or other body is in the elevator entranceway and alters the electrostatic field produced therein. By appropriate control equipment and door actuating apparatus, the operation of such relay effects control of the door or doors of the elevator entranceway in such a manner as to prevent injury to the person who, or object which, by being in the entranceway, caused such relay to operate. Such control of the door or doors of the elevator entranceway may take many forms. In one of the illustrated embodiments of the invention the closing movement of the car and hatchway doors is stopped as a result of the alteration of the electrostatic field in the entranceway by a person or other object therein, and the doors are returned to fully open position before they may be reclosed. In the other of the illustrated embodiments of the invention the closing move ment of the car and hatchway doors is stopped as a result of the alteration of the electrostatic field in the entranceway by a person or other object therein, and the doors are held stationary until such person or object gets out of the entranceway, whereupon the doors resume their closing movement.

In both of the illustrated embodiments of the invention, the equipment is arranged so that, in the event of a failure of an electronic device, or a failure of any other nature which would render ineffective the safety control of the doors, the doors are actuated and prevented from closing similarly as if a person or other object were in the entranceway. A failure which might otherwise go unnoticed thus immediately makes itself known. With such an arrangement, the safety control of the doors always may be relied upon as being effective when the doors open and close normally.

In the event that times may arise when it is desired not to have the safety control for the doors effective, as might occur in the event an electronic device burns out and it is desired to continue to operate the elevator car until the terminal fioor is reached or until repairs can be made, provision is made that, by actuating a suitable switch, the safety control is rendered ineffective. The elevator doors then may be freely operated in either direction.

In accordance with the principles of this invention, provision is made for preventing variations in the electrostatic field in the elevator entranceway, due to causes other than the presence of a person or other object therein, from effecting any influence over the control of the elevator doors. The predominating cause of such extraneous variations in the electrostic field resides in the movement of the doors relative to their surroundings, such as the side of the stationary moulding of the hatchway opening and the side post of the elevator car. In order that variations in the electrostatic field from such causes may, under such cigcumstances, not produce effects simulating those when a person or other body is in the electrostatic field, there is provided a variable condenserhereinafter termed a compensating condenserin the circuit with thecapacity plates from which emanates the electrostatic field. This compensating condenser is actuated in accordance with the movement of the doors, and the arrangement-is such that the capacity change in the electrostatic-field-creating device resulting from the movement of the doorsis compensated for by a complementary change in the capacity of the compensating condenser. Thus, considering the circuit to which are connected both the field-creating condenser and the compensating condenser, there is practically no change in the net capacity therein due to the movement of the doors relative to their surroundings.

Provision may also be made for preventing variations in the electrostatic field, due to movement of the doors relative to their surroundings, from producing effects simulating those when a person or other body is in the electrostatic field by rendering the safety control equipment ineffective after the doors have moved toward closed position a majorportion' of their full-travel. Such an arrangement, when used alone without a compensating condenser, is of value under conditions where it may be desirable to simplify the safety control equipment and to reduce manufacturing and installation costs, or where extreme sensitivity of the safty control equipment is not required,.

such as when it is employed with slow speed door operating equipment. It is to be noted that it is not until the doors have moved toward closed position a major portion of their full travel that the variations from normal of the electrostatic field emanating from the capacity plates on the car door, due to the movement of the doors relative to their surroundings, become very appreciable. With appropriate adjustments in the safety control, the safety control thus may be effectively utilized from the time the doors are at fully open position until they have moved nearly to closed position. Full safety protection during the remaining short distance of door travel to fully closed position may, under some circumstances, be considered as of but little practical value, particularly inasmuch as the doors are then decreasing their closing speed. As a consequence, the lack of control of the doors by the safety control during this short distance may not be considered, under such circumstances, as introducing any real hazard. Especially may this be true when the doors are caused to close by springs, rather than by power. In addition, such an arrangement insures that the doors, after closure, are maintained in closed position while they are intended to be in closed position, regardless of variations in the electrostatic field resulting from any cause, and regardless of whether or not the elevator car is in motion.

If desired, the provision by which the safety control equipment is rendered ineffective after the doors have moved toward closed position a major portion of their full travel, may also be employed when a compensating condenser is provided. Such a compound arrangement may be desirable under certain circumstances where it is desired to have the safety control apparatus effective for a greater proportion of the travel of the doors than is practicable with the arrangement involving no compensating condenser; and yet where it is desired to avoid such refinementof design and adjustment as may at times be necessary when only a compensating condenser is employed.

It is preferred to mount the capacity device upon the elevatorcar, and further, upon the exterior when stationary, isv positioned, is provided by a single capacity device and equipment related thereto, with theprotection to passengers and other objects afforded by such safety control including not only the region in the path of the.

front edge of the car door, but also the region between the car and hatchway doors, and the region in the path of the hatchway door. If desired, however, each hatchway door may be pro vided with a capacity device individual thereto. In such case, the equipment such as the oscillator and the uni-directional current-transmitter and amplifier operatively associated with the capacity device, may be carried by the elevator car. and appropriately connected to the capacity device at the floor opposite which the elevator car, when stationary, is positioned, or this equipment may be positioned at each floor and be individual to the-capacity device at the corresponding fioor. In either case, the capacity device on the hatchway door may be in lieu of, or supplementary to, a capacity device on the car door. When the capacity device on the hatchway door is in lieu of a capacity device on the car door, the capacity device on thehatchway door is arranged so that protection is afforded to passengers and other objects not only in the path of the hatchway door, but also in the path of the car door, and in the region between the hatchway and the car doors. When the capacity device on the hatchway door is supplementary to a capacity device on the car door, each of such two capacity devices afiords protection to passengers and other objects not only in the path of the door upon which it is mounted but also in a region laterally of such door toward the other door. When the capacity device on the car door is supplemented by a capacity device on the hatchway door in this fashion, both capacity devicesmay be operatively connected to the same equipment, such as the oscillator and the uni-directional current-transmitter and amplifier, associated with a capacity device, with such equipment being positioned either on the elevator car or at the floor.

Referring to Figures 1 and 2 of the drawings, an elevator car generally designated 11 is provided with a sliding car door 12 hung from a track 13 by suitable hangers 14. The car door is connected, as by link 15, to a door operating arm 16 which is suitably pivoted, as at 17, to a crosspiece 18 secured to the car frame 20. In the embodiment of the invention illustrated in Figures 1 and 2, the car door 12 is both power opened and power closed, this being effected by means of the electric door operator generally designated 21. Such door operator comprises an electric motor 22 driving, through suitable reduction gearing, a shaft 23 and a ring 24 secured thereto. A connecting member 25, suitably pivoted on ring 24 at a point removed from the axis of shaft23, connects the ring 24 and door operating arm 16. Thus, when the ring rotates clogkwise from the position in which it is shown in Figure 1, the cardoor is moved from open to closed position,' and when the ring is rotated counterclockwise from its position corresponding to closed position, the car door is moved from closed to open position. This is indicated by the arrows in Figure 1 and the letters O (for open) and C (for close) adjacent to the arrowheads.

The ring 24 is provided with cam portions 26 and 27 for actuating suitable limit switches generally designated 30 and 31. The arrangement is such that cam portion 27 actuates limit switch 31 when the car door is in fully open position, and that cam portion 26 actuates limit switch 30 when the car door is in fully closed position. The actuation of the door closed limit switch 30 causes the separation of contacts 32 and 33, while the actuation of the door open limit switch 31 causes the separation of contacts 34 and 35.

A car door interlock switch 36 may be provided, together with a suitable device, such as roller 37 secured to a hanger 14, for actuating the interlock switch to close its contacts when the car door is in fully closed position.

A portion of a hatchway door 38 is illustrated in Figure 1, while a section thereof and its disposition relative to the hatchway opening are illustrated in Figure 2. Suitable toggle links 40 and 41 are provided for locking the hatchway door 38 in closed position. In the embodiment of the invention illustrated in Figures 1 and 2, the hatchway door 38 is coupled to the car door 12 when the elevator car is opposite the floor at which hatchway door 38 is provided, and thus the hatchway door 38 is moved by the door operator 21 on the elevator car along with the car door 12. The coupling between the car door and the hatchway door comprises a channel construction on the car door formed by similar, but oppositely mounted cams 42 and 43. Between cams 42 and 43 is a roller 44 which is mounted on-one end of a bell crank lever 45, the lever 45 being pivotaliy mounted upon the hatchway door, as at 46. A spring 47 is interposed between an abutment 48, provided on the hatchway door 38, and the bell crank lever 45 as illustrated most clearly in Figure 1. The purpose of spring 47 is to bias the bell crank lever 45 into a normal position wherein the upper arm of lever 45 engages the top of abutment 48. When the car and hatchway doors are in fully closed position, the lever 45 assumes such normal position at which time the roller 44 is intermediate, but spaced from, cams 42 and 43. The motion of the car door from fully closed position toward open position results first in taking up the clearance between roller 44 and cam 42, and then in rotating bell crank lever 45 against the action of spring 47. Such rotation of bell crank lever 45 causes the free end thereof to engage the underside of toggle link 40 and raise it upwardly, thereby breaking the toggle'lock for the hatchway door 38. Further motion of the car door in the opening direction then results in a corresponding movement'of the hatchway door in the opening direction.

In accordance with the principles of this invention, there is mounted adiacent to the front edge of thecar door, and on the side thereof adjacent to the hatchway door, a capacitydevice generally designated 50. The construction of the preferred form of this capacity device is best understood by referring to the enlarged section therethrough, shown in Figure 3. There is an elongated metallic trough member 51 mounted on the car door so that the long open side of the trough member is parallel to the front edge of the car door. Mounted in the long open side of the trough member, upon a plurality of suitable insulating blocks 52 appropriately spaced therein, is a flat plate 53 of such a size as to close over a considerable portion of the open side of the trough member. is a metallic plate, 53, parallel to, and in substantially the same plane as, the front edge of the car door, with such plate extending vertically a considerable portion of the door height, and with such plate insulated from its surroundings and located between the planes of the car and hatchway doors.

Suitable means is provided for making electrical connection to the plate 53. This may be, as illustrated in Figure 3, a pin 54 extending through the plate 53 and one of the blocks 52 and thence through the back of trough member 51. An insulating bushing 55 prevents contact of pin 54 with the trough member, and suitable securing nuts are provided to enable the making or a connection to pin 54. Also, it is preferred that means, such as screw 56, be provided for making electrical connection to the surrounding trough member 51.

Referring again to Figures 1 and 2, there is shown secured to the door operating arm 16, as by cleats 57, a pair of cables, designated 58 and 60. Cable 58 is connected to trough mem ber 51 by screw 56, while cable 60 is connected to the plate 53 by being connected to pin 54. Preferably these cables, or at least cable 60, are provided with a metallib sheath, the desirability of which will appear later.

The upper ends of cables 58 and 60 leave the operating arm 16 near its pivot 17 and proceed to an enclosed box generally designated 61. Within box 61 may be provided much of the equipment for eifecting the control of the doors in accordance with the principles of this invention. Box 61 may be mounted at any convenient locationit may even be mounted, when suitably proportioned on the car door 12 adjacent to capacity device 50, or at some other convenient location on the car door, if desired-but it is preferred to mount it on cross piece 18 near the pivot 17 for the operating arm 16. The equipment which is advantageously mounted within box 61 is diagrammatically shown in Figure 5 as encompassed within the broken outline designated 61. Preferably the box is formed of metal so that'it may act as a shield, and be grounded.

The embodiment of the invention illustrated in Figures 1 and 2 includes, in addition to the equipment previously mentioned, a compensating condenser, generally designated 62, actuated in accordance with the position of car door 12. Such compensating condenser may be of any suitable construction. For purposes of simplicity, it is shown-referring to Figure 4-as comprising a plurality of stationary plates 63 between each adjacent pair of which is a movable plate 64.- The stationary plates 63 are suitably connected together and to an end piece 65 which may be secured to an insulating base 66. The movable plates 64 are likewise suitably connected together and to an end'piece 67. Each movable plate is spaced and insulated from the stationary plates adjacent thereto. To the end piece 67 is secured, as by screw 68, a rod 70 which extends through a bearing formed in end cover 71. Longitudinal movement of rod 70 to the left, as viewed in Figures 1 and 4, results in withdrawing the movable plates 64 from between the stationary plates 63, while longitudinal movement of rod 70 to the right results in advancing the movable plates The resulting construction 64 into the spaces between the stationary plates 63. Movement of the movable plates '64 in accordance with the position of the car door 12 is effected by suitably connecting rod todoor operating arm 16. Such connections may comprise, as illustrated, a connecting rod 72 provided with a clevis '73 at one end pivotally secured to arm 16, and provided with a clevis 74 at its other end pivotally secured to a head 75 mounted on the end of rod 70. Preferably the equipment connecting rod 70 with door operating lever 16 is provided with means for adjusting the total amount of movement imparted to the movable plates 64 and for adjusting a given total amount of movement relatively to the stationaryplates 63. The former adjustment may be obtained by adjusting the point of pivotal connection of clevis 73 with arm 16. The latter adjustment may be obtained by varying the distance between clevis '73 and elevis '74. In addition, it is preferred that the total number of plates, both in the stationary set and in the movable set, may be varied, and to this end both sets of plates are constructed so that they may be readily removed and plates added to or subtracted therefrom. As illustrative of such a construction, the set of stationary plates 63'are secured together and to end piece 65 by means of bolts 76, and the set of movable plates 64 are secured together and to end piece 67 by means of bolts 7'7. In order to insure that the set of movable plates 64 may, after removal for adding or subtracting plates, be repositioned on rod '70 at the same point, rod 70 is preferably provided with a slot or ring into which fits the end of screw 68.

The function of the compensating condenser 62, and the shape of its plates by which it effects such function, will be described later.

The compensating condenser 62 is preferably provided with a metallic cover '78, both for the purpose of affording protection to the condenser against dirt and other foreign matter, and for the purpose of acting as an electric shield. In the construction illustrated, the end cover 71 is also of metal, and both the cover '78 and the end cover 71 are secured to the metallic angle shape upon which the condenser rests, so that the set of stationary plates 63 are completely shielded from external influences.

In Figure 5 there is shown a schematic wiring diagram for the equipment heretofore described. The electromagnetic switches employed in the diagram are designated as follows:

A-Car-in-motion relay BDoor safety switch CDoor control relay DAuxi1iary door control relay DCDoor closing switch DO-Door opening switch LR,Latching relay Throughout the following description, these letters are applied as prefixes to the reference numbers for the parts of the above designated switches. Thus, for example, C146 indicates contacts of the door control relay.

The box 61 is shown in Figure 5, as mentioned above, in dotted outline. The outline is connected, as at 81, to a ground such as the car frame, or to the grounded side of an elevator control or power circuit, to indicate that the contents of the box are shielded from outside influences by a grounded shield.

The compensating condenser 62 is shown as enclosed within a dotted outline which is grounded by virtue of being connected to conductor 82, and thus, by way of conductor 58, to the ground conductor 81. The shield for condenser 62 is also grounded by virtue of its electrical connection with the metallic sheath around a conductor 83 i with the shield for box 61, and thus is grounded.

The metallic sheath around conductor 60 may also be grounded, if desired, by connecting it to the trough member 51.

The equipment within box 61 comprises generally a generator of high frequency oscillations, 84, and a receptor and rectifier of such oscillations, 85. The generator 84 includes a triode vacuum tube 86 with its grid and plate connected to a tuned circuit made up of inductance 87 and condenser 88. Condenser 88 is preferably variable so that a control of the frequency of oscillation may be had. A suitable blocking condenser 90 is inserted between the plate of the vacuum tube 86 and the tuned circuit. The filament of the vacuum tube 86 is energized from the direct current source of supply as follows: from the negative main, by way of knife switch blade 91. conductor 92, resistances 93 and 95, filament of generator vacuum tube 86, filament of rectifier vacuum tube 96, resistance 97, conductor 98, safety control disabling switch 100 and knife switch blade 101, to the positive main. The junction point 94 between resistances 93 and 95 is connectedto generator inductance 87, preferably by an adjustable device'102. The plate of the generator tube 86 is maintained at an appropriate potential with respect to its filament by the voltage rise across resistance 97 since the plate of the generator tube 86 is connected, preferably through a suitable high frequency choke coil 103, to conductor 98.

The rectifier 85 comprises a triode vacuum tube96 with its input or grid-filament circuit connected across an inductance 104, and with its output or plate-filament circuit connected to energize the actuating coil B of the door safety switch B. The plate of the rectifier tube 96 is maintained at an appropriate potential with respect to its filament by means 01' the voltage rise across resistance 9'7, similarly as with the generator tube. Suitable by-pass condensers are provided; one, designated 106, is connected between conductor 92 and the junction 108 of the filament circuits for the generator tube and the rectifier tube filaments: a second, designated 107, is connected between junction 94 and junction 108; and a third, designated 110, is connected from the plate of the rectifier tube 96 to Junction 108.

Inductance 104 is inductively related to inductance 87 of the generator (as diagrammatically represented by the dotted arrow 111) so that high frequency oscillations of the frequency generated by generator 84 are induced in theinductance 104. In parallel with inductance 104 is a circuit containing condensive reactance to form therewith a tuned circuit, for convenience generally designated 112. Such condensive reactance comprises, in the embodiment of the invention illustrated in Figures 1-5, the capacity device 50 on the front edge of the car door, the compensating condenser 62, and a condenser 113. As shown in Figure 5, compensating condenser 62 is in parallel with capacity device 50, and the two are in series with condenser 113. The value of inductance 104 and of the capacities in the condensive reactive cir cuit paralleling inductance 104 are such that, when the doors are in open position and no person or other body is in the elevator entranceway, tuned circuit 112 is in resonance with the oscillations produced by the generator 84. Thus, considering the relative magnitudes of the peaks of the resulting high frequency voltage existing across the terminals of inductance 104, the magnitude of such voltage is a maximum when tuned circuit 112 is in such resonant condition. The high frequency alternating current voltage impressed across the input of rectifier tube 96 is thus of maximum magnitude when tuned circuit 112 is in such resonant condition. I

When a person or other body is positioned in the elevator entrancewayi. e., is positioned in the region in front of the car door or the hatchway door, or in the region between the car and the hatchway doors-and thus is in the electrostatic field emanating from capacity device 50, the capacity of such device is thereby altered so that timed circuit 112 is detuned from resonance with the oscillations produced bygenerator 84. The magnitude of the high frequency voltage existing across the terminals of inductance 104, and thus the magnitude of the high frequency voltage impressed across the input of rectifier tube 96, is then of a magnitude less than that when tuned circuit 112 is in resonance with the oscillations produced by generator 84.

The rectifier tube 96 rectifies the high frequency energy impressed across its input and delivers in its output circuit rectified current having an average or root-mean-square value which is dependent upon the magnitude of the high-frequency potential impressed across the rectifier tube input. In the illustrated embodiments of the invention, the arrangement is such that when the maximum magnitude of the high frequency voltage is impressed across the input of the rectifier tube--resulting when tuned circuit 112 is in resonance with the oscillations produced by generator 84the output current of rectifier tube 96 is a maximum value. When tuned circuit 112 is out of resonance with the oscillations produced by generator 84, the output current of rectifier tube 96 is at a value less than such maximum value.

The percentage change in the output current when tuned circuit 112 is detuned from resonance a given amount is preferably made to be considerably greater than the percentage change in the magnitude of the high frequency voltage impressed across the input of rectifier 96 that caused such change in the output current. Adequate sensitivity of the safety control of this invention, without resort to delicate and complex switching mechanisms responsive to very small changes in the rectifier output current, is thus obtainable. In the illustrated embodiments of the invention, such increase in the percentage changes in the output of the rectifier over the percentage changes in the input of the rectifier is procured by operating rectifier tube 96 with a large negative bias on its control grid, and by utilizing the lower bend of its grid potential-plate current curve for the purpose of rectification. This is illustrated in Figure 6. In Figure 6 the grid potential-plate jection of curve 116 for time t: results in the peak of curve 118 at time tz. At times t; and ts, the value of the high frequency voltage impressed current characteristic of a suitable triode vacuum tube is shown by curve 114. The bend 115 of such curve is the lower bend thereof. The upper portion of the characteristic curve, and the upper bend thereof, are not shown. Curves 116 and 117 are time curves of the high frequency voltage existing across the terminals of inductance 104, and thus of the high frequency voltage impressed across the input of the rectifier tube. Curve 116 illustrates the high frequency input voltage when tuned circuit 112 is in resonance with the oscillations produced by generator 84, while curve 117 (in dotted outline) illustrates the high frequency input voltage when tuned circuit 112 is detuned from resonance with the oscillations produced by generator 84. Due to the large negative bias with which the control grid of rectifier tube 96 is impressed (resulting from the voltage rise across resistances 93 and and the filament of oscillator tube 86), the line of no-voltage for curves 116 and 117 intercepts the E; coordinate of the grid potential-plate current curve of the rectifier tube considerably to the left (as viewed in Figure 6) of the bend 115 in the characteristic curve 114.

Curve 118 represents the plate current output of the rectifier tube, plotted against time, when the rectifier has impressed across its input voltage represented by curve 116. Curve 119 represents the plate current output of the rectifier tube, plotted against time, when the rectifier has impressed across its input voltage represented by 'curve 117. Curve 1113 may be obtained by projecting various points upon the curve 116 up to the characteristic curve 114 and then projecting the points of intersection of such projections with the characteristic curve 114, over horizontally to the right until they are at points representing instants of time identical, respectively, with the instants of time for the points of projection from curve 116. Thus, at time ti, the projection of the curve 116 up to the characteristic curve 114 results in a value of output plate current I as shown by curve 118 above the point t1. Similarly, a proacross the input of the rectifier tube is the same as the value at time t1. At time t4, the value of the high frequency voltage impressed across the input of the rectifier is of a magnitude equal to that at time t2 but of a polarity opposite thereto. Due to the fiat characteristic of the curve 114 for the rectifier, the output current Ip for time t4 is of a minute value. The output current Ip is therefore of negligible value during the negative cycle of the impressed high frequency voltage. When the impressed high frequency voltage is in its positive cycle, and particularly when, during such positive cycle, it is of such a magnitude as to carry the net potential of the control grid of the triode tube over to the portion of its characteristic curve between the lower and upper bends of such curve, the output current I is considerable. The average value for the rectifier output current having variations in accordance with curve 118 is diagrammatically represented by the horizontal straight line 120.

By a process similar to the above, the rectifier output current curve 119 may be derived from the high frequency voltage input curve 117. The average value for the rectifier output current having variations in accordance with curve 119 is represented by the horizontal broken line 121.159

From Figure 6 it may be seen that the average value of the rectifier output current, 121, resulting when the tuned circuit 112 is detuned from resonance with the oscillations produced by the generator 84, is considerably less than the average value of the rectifier output current, 120, resulting when the tuned circuit 112 is in resonance with the oscillations produced by the generator 84. It may also be seen that-the percentage decrease in the average value of the output current is considerably greater than the percentage decrease in flowing through coil B105 decreases from such maximum value a given amount, the coil B105 is ineffective to maintain contacts B122 separated, so that contacts B122 reengage. In other words,

when tuned circuit 112 is in resonance with theoscillations produced by generator 84-which is when no person or other body is in the elevator entranceway and in the field of capacity device 50contacts B122 are disengaged. When tuned circuit 112 becomes detuned from resonance with the oscillations produced by generator 84- which is when a person or other body is in the elevator entranceway and in the field oi capacity device 50-contacts B122 are in engagement.

Continuing with the. description of the schematic wiring diagram of Figure 5, let it be assumed that knife switches 91 and 101 are closed to connect the equipment to the source of supply, and that safety control disabling switch 100 is closed to render the safety control eflective. The oscillation generator 84 thereupon becomes effective to generate high frequency oscillations. These oscillations are impressed across inductance 104 of tuned circuit 112 which, assuming that the car and hatchway doors are in open position and that no person or other body is in the field of capacity device 50, is in resonance with such oscillations. The rectifier 85 trans lates the high frequency energy impressed upon it to a form suitable to operate door safety switch B, and, under the circumstances assumed, such translated or rectified energy causes switch B to operate and effect the separation of contacts B122.

There is provided for elevator car 11 a control device or other suitable instrumentality to control the opening and closing of the car and hatchway doors. As representative of such an instrumentality, there is shown in Figure 5 .a pair of contacts 123 which are closed by such instrumentality when it is desired to open the car and hatchway doors, and a pair of contacts 124 which are closed by such instrumentality when it is desired to close the car and hatchway doors.

' the elevator car. In the embodiment of the invention illustrated in Figure 5, contacts 123 and l24 need be caused to engage only momentarily, and thus could be push buttons controlled directly by an operator within the elevator car, if desired.

Let it be assumed that the system of Figure 5 is controlled by a car operator, and that such car operator, desiring to close the car and hatchway doors, causes the engagement of contacts 124. A circuit is thereby completed as follows: from the minus main, by way of contacts A125 of the car-in-motion relay (which are closed since the elevator car is stationary), contacts 124, contacts C126 of the door control relay, reset coil LR127 of the latching relay, to the plus main.

The resulting energization of the reset coil LR127 causes the release of the latch 128 for the armature 130 of the latching relay, and, as a consequence, latching relay contacts LR131 separate and latching relay contacts LR-132 engage. The design of latching relay LR is such that the contacts LR131 and LR132 remain in the positions to which they are operated after the reset coil LR127 is deenergized. Subsequent disengagement of the contacts 124 is thus of no effect.

The engagement of contacts LR132 of the latching relay completes a circuit for the actuating coil DC133 of the door closing switchby way of contacts 33 of the door close limit switch, interlock contacts D0134 of the door opening switch and contacts C135 of the door control relay. The resulting actuation of the door closing switch DC causes the engagement of contacts D0136 and DC137 and the separation of contacts D0138. The engagement of contacts D0136 and D013? causestheenergization of armature 140 of the electric door motor 22 of door operator 21. The field 141 of the electric door motor was energized when the knife switches 91 and 101 were closed to connect the equipment to the source of supply. The separation of contacts DC138 removes resistance 142 as a shunt around the armature 140. The door motor 22 thus operates to cause the clockwise rotation of ring 24, and thus, to cause the closing of the car and hatchway doors in the manner previously described.

Attendant upon the movement of the car door away from fully open position, the door open limit switch 31 returns to its normal position with contacts 34 and 35 in engagement. The engagement of contacts 34 causes the energization of actuating coil D143 of the auxiliary door control relay, and, as aconsequence, contacts D144 engage. The engagement of contacts D144 is without effect at this time, however, since contacts C145 of the door control relay are separated. The engagement of contacts 35 of the door open limit switch is of no effect, inasmuch as contacts C146 of the door control relay and contacts LR131 of the latching relay are separated.

As the car and hatchway doors are in the process of closing, compensating condenser 62 is actuated by the operating arm 16. The design and construction of compensating condenser 62. and its capacity variations in accordance with movement of the operating arm 16 are such that, in the event variations occur in the electrostatic field emanating from the capacity device 50 onthe edge of the car door while the door is in the process of closing, as a result of causes other than the presence of a person or other body in the path of the car door or the hatchway door, such compensating condenser counteracts the tendency of such variations to detune the tuned circuit 112. and thus maintains the tuned circuit 112 substantially in resonance with the oscillations which are produced by generator 84. With the arrangement illustrated in Figures 1-5, the shape of the movable plates 64 of compensating condenser 62 is such that the capacity thereof is a maximum when the doors are in open position, and is a minimum when the doors are in closed position, with-the change from the maximum to the minimum capacity being at first gradual as the doors move from open position, and then progressively increasing in rate as the doors approach closed position. .In this fashion the major variations in the electrostatic field, due to motion of capacity device 50 relative to the side post of the elevator car and to the jamb of the hatchway opening while the doors are closing, are compensated for. It is therefore assured that contacts B122 are maintained separated while the doors are closing, assuming no person or other body obstructs the doors; even though the mere movement of the doors in closing results in a change in the field emanating from the capacity device 50.

As the car and hatchway doors near fully closed position, door close limit switch 30 is actuated to cause theseparation of its contacts 32 and 33. The separation of contacts 32 causes the deenergization of actuating coil D143 of the auxiliary door control relay, and as a consequence contacts D144 separate. The separation of contacts 32 does not affect the actuating coil 0147 of the door control relay C, inasmuch as, under the circumstances assumed, actuating coil C147 was not energized during the closing of the doors. The separation of contacts 33 of the door close limit switch causes the deenergization of the actuating coil DC133 of the door closing switch, and, as a consequence, this switch returns to its initial position with contacts D0136 and D0137 separated and contacts DC138 in engagement. The armature of the door motor 22 is thereupon deenergized, and is rapidly brought to a standstill by the dynamic braking action of resistance 142.

When the door motor 22 becomes stationary, the car and hatchway doors are in fully closed position. In this position, the appropriate contacts in the elevator control circuits, such as gate contacts 36, which are responsive to the positions of the car and hatchway doors, are in engagement so that the elevator car may then be moved. The

.manner by which the elevator car 11 may be moved, and the circuits by which such movement may be controlled, are not shown;

When the elevator car is in motion, actuating coil A148 of the car-in-motion relay is energized in any appropriate manner from the equipment controlling the motionof the elevator car. Contacts A125 are thus separated when the car is in motion, and as a consequence the door operator 21 is prevented from being operated while the elevatorcar is in motion.

As the elevator car becomes stationary opposite a floor, the operator within the car, desiring to open the car door and the hatchway door for the floor opposite which the car is positioned, may cause the engagement of contacts 123.- If desired, additional mechanisms may be provided, which are automatically operable as the car becomes stationary opposite a floor, to duplicate the effect of an engagement of contacts 123. The engagement of contacts 123 completes a circuit for the actuating coilLR150 of the latching relay. This circuit'may be traced from the minus main, by way of contacts A125, contacts 123, actuating coil LR150. to the plus main. The resulting energization of actuating coil 13150 causes the movedoor closing relay. The engagement of contacts LR131 causes the energization of the actuating coil D0151 of the door opening switch, by way of contacts 35, actuating coil D0151 and contacts LR131. The resulting operation of the door opening switch causes the engagement of contacts D0152 and D0153 and the separation of contacts D0134 and D0154. The engagement of contacts D0152 and D0153 connects the armature 140 of the door motor 22 to the source of supply in the manner reverse to that effected by the engagement of contacts D0136 and DC137 of the door'closing switch. The separation of contacts D0154 removes the resistance 142 as a shunt around armature 140. Inasmuch as the motor field 141 is continuously energized, the door motor thereupon operates to rotate ring 24 in the counterclockwise direction. and thus to effect the opening of the car and hatchway doors in the manner previously described. The separation or contacts D0134 is further assurance that actuating coil DC133 of the door closing relay remains, deenergized.

As the car door moves away from fully closed position, the door close limit switch 30 returns to its initial position with contacts 32 and 33 in engagement. The engagement of contacts 32 completes a circuit for the actuating coil D143 of the auxiliary door control relay D by way of contacts 32 and 34. The resulting engagement of contacts D144 is, under the circumstances assumed, of no effect, inasmuch as contacts C145 of the door control relay are separated. The engagement of contacts 33 of door close limit switch 30 is of no effect, inasmuch as contacts D0134 and contacts LR132 are separated.

While the car and hatchway doors are being opened, compensating condenser 62 is being returned to its initial position as illustrated in Fig- 125 ures 1 and 4.

As the car and hatchway doors near fully open position, door open limit switch 31 is actuated to cause the separation of contacts 34 and 35. The separation of contacts 34 results in the deenergization of actuating coil D143, and thus, in the separation of contacts D144. The separation of contacts 35 causes the deenergization of actuating coil D0151 of the door opening switch, and as a consequence this switch drops back to its initial position with contacts D0152 and D0153 separated and contacts D0134 and. D0154 in engagement. The separation of contacts D0152 and D0153 effects the deenergization of the armature of thedoor motor and the engagement of contacts D0154 brings the armature of the door motor to a quick stop as a result of the action of dynamic braking resistance 142. The engagement of contacts D0134 is in preparation for a door closing operation. The car and hatchway doors thus become stationary in their fully opened positions.

It will be recalled that. when a'person or other body gets nto the electrostatic field'produced;

in the elevator entrance way by. the capacity device 50, contacts B122 thereupon immediately engage. Let it be assumed that, while the car and hatchway doors are stationary in their fully open positions, contacts B122 are thus caused to engage as a result of a person or other body being in the elevator entranceway. A circuit is thereby completed for actuating coil C147 01 the door control relay by way of contacts 32 of the door close limit switch. The resulting opera-' tion of switch C causes the engagement of contacts C145, C146 and C155, and the separation of contacts C126 and C135. The engagement of contacts C145 is or no efiect since contactsD144 of the auxiliary door control relay are separated. The engagement of contacts C146 is of no effect inasmuch as contacts of the door open limit switch are separated. The engagement of con tacts C155 completes a circuit for actuating coil LR150 oi the latching relay. The resulting energization of the actuating coil LR150 is of no eflEect, however, inasmuch as armature 130 is already latched in the position in which contacts LR131 are in engagement and contacts LR132 are separated. The separation of contacts C126 and C135 renders ineffective, respectively, the close contacts 124 and the door closing switch DC. Door motor 22 thus cannot be energized to close the car and hatchway doors. This condition continues as long as contacts B122 are in engagement, and thus, as long as the elevator entranceway is obstructed by a person or other body in the field of capacity device 50.

Let it be assumed that, while. the car and hatchway doors are in the process of'closing, contacts B122 are caused to engage as a result of a person or other body being in-the elevator entranceway. It will be recalled that to effect the closing of. the car and hatchway doors, close contacts 124 are engaged, reset coil LR12'7 is energized, contacts LR131 are separated, contacts LR132 are engaged and actuating coil D0133 is energized. It will also be recalled that the movement of the car and hatchway doors away from fully open position causes the engagement or. contacts 34 and 35 of the door- -open limit switch, and that the engagement of contacts 34 results in the actuation of auxiliary door control relay D and the engagement of contacts D144. Thus, the presence of a person or other body in the hold of capacity device 50 while the car and hatchway doors are closing, and the resulting engagement of contacts B122, completes a circuit for actuating coil C147 of the door control relay C. This circuit is from the minus main, by way of door close limit switch contacts 32, actuating coil C147 and contacts B122, to the plus main. Door control relay C is thereupon operated to cause the engagement of contacts C145. C146 and C155 and the separation of contacts C126 and The separation of contacts C135 immediately deenergizes actuating coil D0133 of the door closing switch, which thereupon drops out. The engagement of contacts C146 completes a circuit for actuating coil D0151 of the door opening switch, which is thereupon actuated. The dropping out of the door closing switch DC and the actuation of the door opening switch D0 first brings the door closing movement of the car and hatchway doors to a stop and then causes the opening of the car andhatchway doors. The separation of contacts C126 renders the close contacts 124 ineffective, while the engagement of contacts C155 energizes actuating coil LR150 of even though the obstructing person or body in the elevator entranceway that caused the engagement of contacts B122 moves, or is removed, from the entranceway and thus from the field of capacity device 50. As a consequence, in spite of the resulting reseparation of contacts B122, door motor 22 continues to return the car and hatchway doors to their initial, fully open position. Such door opening operation of the doors may not be interrupted by causing the engagement of close contacts 124, since these contacts are rendered inefiective by the separation of contacts C126.

As the doors near fully open position, door open limit switch 31 is actuated to cause the separation of contacts 34 and 35. The separation of contacts 35 deenergizes actuating coil D0151 of the door opening switch DO, with the result that the door motor 22 isdeenergized and the door is brought to a stop at fully open position. The separation of contacts 34 deenergizes actuating coil D143 of the auxiliary door control relay. The resulting separation of contacts D144 interrupts the holdingcircuit for actuating coil C147 of the door control relay, so that this relay returns to its initial position. The resulting reengagement of contacts C126 and C135 does not of itself initiate a door closing operation, since latching relay LR is in the position normally incident to a door opening operation in which contacts LR132 are maintained separated by latch 128. To reclose the car and hatchway doors, "close contacts 124 must be reengaged.

In the event a person or other body is in the field of capacity device 50 while the doors are in the process of opening, contacts B122, as in the other cases, are caused to engage.

circuit including contacts C145 and D144. The actuation of door control relay C under these circumstances, however, does not interrupt the door opening operation. It insures that the doors are moved to fully open position before they are reclosed.

Doorcontrol relay C is thereupon operated, and is maintained in actuated position by the holding It will be recalled that shortly before the doors attain closed position, contacts 32 of the door close limit switch are caused to separate. The separation of these contacts prevents energization of actuating coil C147 of the door control relay while the car and hatchway doors complete their movements to fully closed position, and while such doors are in fully closed position. Contacts B122, and thus the action of capacity device 50, are rendered inefiective so long as contacts 32 are maintained separated.

The separation of contacts 32 thus insures the closure of the doors to their fully closed position in the event the compensation ailorded by compensating condenser 62 for the changes in the be effected by adjustment of cam portion 26 circumferentially on ring 24.

Itis to be noted .thatin the event either or both vacuum tubes 86 and 96 burn out,.or in the event of a failure of any other nature in the tubes or apparatus associated therewith. while the car and hatchway doors arein open position, actuating-coil B105 of the door safety switch is deenergized and contacts B122 engage. The engagement of-contacts B122, as previously .explained, results in preventing the closing of the car and hatchway doors. This action of contacts B122 continueseven though the close" contacts 124 are caused to engage by the car operator orin some other fashion. Since thedoors will not close, arid since the car cannot move until the doors are closed and the gate contacts, such as contacts 36, engage, the failure of the safety control for the doors is immediately brought home to the car operator'or other person attempting to operate the car. Investigation'and repair of the safety control for the doors will therefore be promptly made. In the event it is desired to operate the car temporarily without the safety control until repairs thereto can be made, there is provided a safety control disabling switch 100, which, when open, renders the entire safety control for the doors ineffective. With switch 100 open, the,doors may continue to be operated in the usual manner without the safety control, .by the actuation of open" contacts 123 and close" contacts 124 as before.

In the event offailure of either or both of vacuum tubes 86 and 96, or .of any apparatus associated therewith, while the elevator car is in motion, it is to be observed that the resulting engagement of contacts B122 does not affect the continued operation of the elevator car until the car has been brought to a stop at a floor in accordance with thenormal action of the car actuating and stopping mechanisms and until the opening of thecar and hatchway doors has been started. It is then that the engagement of contacts B122 becomes effective to insure the open- .Ling of the doors tofully open position and the maintenance of the doors in such position (and thus, to prevent further motion of the elevator car), until theapparatus failure is repaired, or until the safety control disabling switch is opened.

Figures 7 and 8 illustrate a second embodiment of the invention. The elevator car, generally designated 200, is provided with a sliding car door 201 hung from a track 202 by suitable hangers 203. The car dooris connected, as by link 204, to a door'operating arm 205 which is suitably pivoted as at 206, to a crosspiece 207 secured to the car frame 208.

In this embodiment of the inventio'n, the car door'201 is power opened and spring closed. The closing of the car door is effected by a spring 210, one end of which is secured to door operating arm 205. The other end of spring 210, may 75. suitably secured to the car frame, as by chain 211 and pin 212. The opening of door 201 iseffected by means of the electric door operator generally designated 213. Such door operator comprises an electric motor 214 driving the shaft 215 which, through suitable reduction gearing 216, drives a second shaft 217. Upon slow speed shaft 217 is secured a member 218 having two eccentric drum portions 220 and 221. A chain 222 or other suitable flexible member is secured to member 218 and arranged to be wound around eccentric drum portion 220. The free end of chain 222 is secured to door operating arm 205 as at 223.

The car door is opened by power when motor 214 is driven so as to cause chain 222 to be wound upon eccentric drum portion 220. The closing of the car door 201 is effected by the action of the mechanically operated limit switches 226 and 227.

These may be conveniently of the construction shown in Figures 7 and 8 and arranged to be actuated by a pin 228 mounted upon member 218. With the position of the equipment illustrated in Figure 7, the car door is in open position..- As a consequence, thecontacts of open limit switch 228 are separated, while the contacts of close limit switch 227 are in engagement Door operator 213 also is effective to open the hatchway door for thefioor at which the elevator car has stopped. This is illustrated somewhat diagrammatically in Figure 8. Hatchway door 230, supported upon track 231, is provided with toggle arms 232 and 233. Hatchway door 230 is spring closed by spring 234, one end of which is secured to the door frame while the other end is secured to outer toggle arm 233. To open hatchway door 230, toggle arm 232 is raised. This action also distends door closing spring 234. To

raise toggle arm 232 a long retiring cam 235 is provided on the car. Retiring cam 235 is pivotally mounted upon suitable members secured to the car frame 208. A chain 236 or other suitable flexible member is secured at one end to retiring cam 235 and at the other end to drum portion 221 of member 218. The arrangement is such that chain 236 is wrapped around eccentric drum portion 221 while chain 222 iswrapped around eccentric drumportion 220. Thus, cam 235 is raised and projected outwardly by motor 214 concurrently with the opening of the car door.

Cam 235 engages with a bell crank lever 237 pivotally mounted adJacent the sill of the hatchway door. The engagement of cam 235 with bell crank layer 237 causes lever 237 to rotate counterclockwise, as view in Figure 8, thereby raising rod 238 whichin turn raises rod 240. Rod 240 is secured to toggle arm 232. As rod 240 is raised, .the hatchway door is opened. A check 241 may be provided for checking the door as it nears door open position, the actuating member of the check being pivotally-secured to one end of a lever 242,

the other end being secured to the junction of rods 238 and 240. Lever 242 is pivotally supported intermediate its ends from the door frame as at 243. A second check, 244, is preferably connected between the door frame and toggle arm 232' so as to check the hatchway door as it nears closed position.

Door operator 213 on the elevator car effects the opening of the car door 201 and the hatchway door 230. The closing of the car and hatchway doors is effected by the action of the closing springs individual thereto. During the closing of the doors, door motor 214 may be returned to its initial position either mechanically or electrically.

For the purpose of simplification, it is assumed in the following description that door motor 214 is returned to its initial position by mechanical means such as a spring. This 'could be, if desired, by the car door closing spring 210.

There is mounted upon car door 201, adjacent the front edge thereof, a capacity device 50 similar to the corresponding device mounted upon car door 12 of Figures 1 and 2. Suitable connections are provided between capacity device 50 and box 61 mounted upon the framework of the elevator car. Within box 61 is contained much of the equipment for effecting the control of the doors in accordance with this invention.

A car door interlock switch 245 is provided together with a suitable device, such as a roller 246 secured to a hanger 203, for actuating the inter lock switch to close its contacts when the car door is in its fully closed position.

In addition to interlock switch 36, roller 24 engages with a door actuated safety control dis-.

abling switch 247. The contactsof this switch are maintained in engagement until the car door has closed asubstantial portion of its total movement. Roller 246 then causes the contacts of door actuated safety control disabling switch 247 to separate. These contacts remain separated during the remaining portion of the closing operation, and while the doors remain in closed position. As roller 246 engages with switch 247 during an opening operation of the doors, the contacts of switch 247 are caused to reengage. Any suitable switching equipment, controlled as above, could be employed. For simplicity, the switch 247 has been illustrated as a spring biased toggle type.

Slow speed shaft 217 preferably controls a shaft switch generally designated 248 and illustrated in detail in Figure 9. Shaft switch 248 comprises a pair of contacts 250 which are caused to separate and remain separated while shaft 217, and thus door motor 214, are operating in the door opening direction, and which are caused to engage and remain engaged while shaft 217, and thus door motor 214, are operating in the door closing direction. Such operation of contacts 250 may be conveniently effected by the mechanisms shown in Figure 9, wherein a collar 251 surrounding shaft 217 is provided with a friction member 252 urged against shaft 217 by a suitable spring 253. Collar 251 is provided with an extension 254 at the end of which there is a recess to accomrnodate the end of a toggle member 255. The other end of toggle member 255 is pivotally secured to a lever 256 which in turn is pivotally supported on a stationary piece 257, as illustrated in Figure 9. Surrounding toggle member 255 is a spring 258 acting between extension 254 of collar 251 and a shoulder on toggle member 255 near its pivotal support. As a result of the illustrated construction of shaft switch 248, its contacts 250, actuated by lever 256, are caused to en gage when slow speed shaft 217 rotates in the clockwise, or door closing, direction, and are maintained in engagement after cessation of such rotation by the toggle switch action of extension -254, toggle member- 255, spring 258 and lever 256 until positively separated due to the rotation of shaft 217 in the counterclockwise, or door opening, direction.

In Figure 10, there is shown a schematic wiring diagram of the embodiment of the invention illustrated in Figures 7, 8 and 9. The electromagnetic switches employed in this diagram are designated as follows:

BDoor safety switch (as in Figure 5) CDoor control relay (as in Figure 5) DC-Door closing switch (as in Figure 5) DO--Door opening switch (as in Figure 5) P-Up direction relay Q-Down direction relay R-Car control relay SAuxiliary car control relay TDoor opening sequence relay U-Door motion switch Throughout the following description, these letters are applied as prefixes to the reference numerals of the parts of the above designated elements. Thus, for example, C294 indicates contacts of the door control relay C.

The equipment within box 61' of Figure 10 is similar to the equipment within box 61 of Figure 5. As a consequence, the same reference numeral has been employed to designate this equipment in the two wiring diagrams. Similarly, capacity device 50 may be the same for both wiring diagrams. It is therefore unnecessary to repeat the description of the operation of the equipment within box 61. It is believed suflicient to point out that, when the safety control equipment within box 61 is effective (at which time knife switches 260, 261 and 262 are closed and contacts R263 are in engagement), contacts B122 of the door safety switch are maintained separated so long as the electrostatic field emanating from capacity device 50 is not materially changed. -When the electrostatic field produced by capacity device 50-is changed due to the presence of a human being or other body thereinwith a resulting change in the net capacity of the circuit in which capacity device 50 is connected--the current through actuating coil B105 of the door safety switch becomes insuflicient to maintain contacts B122 separated. As a consequence, contacts B122 of the door safety switch engage.

The invention illustrated in Figure 10 is shown in conjunction with an elevator control system of the type in which the starting of the elevator car is under the control of an operator therein, while the stopping of the car is normally controlled by push buttons for the various floors either in the halls or in the car or both. Only a portion of such an elevator control system is illustrated in Figure 10 and that portion, for simplicity, is illustrated diagrammatically.

Within the elevator car and under the control of an operator thereof, is an operator's handle 270, shown in Figure 10 in the neutral position. When the handle 270 is moved to Close, the car and hatchway doors are caused to move to closed position. When handle 270 is moved to Start, the car is caused to start and move in either the up or the down direction, determined by whichever one of the car direction relays P or Q is then operated. The manner in which the actuating coils P271 of the up direction relay P and Q272 of the down direction relay Q are energized and controlled is foreign to this invention. When handle 270 is moved to Open, the car and hatchway doors are caused to move to open position.

Car control relay R, subject to contacts P275 and Q322 of the car direction relays P and Q, and subject to car door interlock contacts-245, to hatch door interlock contacts 273 (shown as one made.

contact in place of a number of contacts, in series, one contact at each floor), to operator's handle 270, and to contacts S291 of auxiliary car control relay 8, causes, when actuated, the starting of the elevatorcar through the intermediary of its contacts R264 and of other equipment, not shown in Figure 10.

The stopping of the elevator car in response to actuated push buttons is effected by equipment also not illustrated in Figure 10. Itis believed sufiicient'to note that, as an incident in each stop of the elevator car, contacts 274 are caused to engage momentarily as the car approaches the floor levelfor the fioor at which a stop is being Contacts 274, hereinafter referred to as stop contacts, may be operated in any convenient manner, and either electrically or mechanically.

Continuing with the description of the schematic wiring diagram of Figure 10, let it be assumed that the elevator car is stationary, that the car door and the hatchway door for the fioor at which the car is positioned are stationary, each in its fully open position, and that the actuated direction relay 'is the up direction relay P, so

that as a consequence contacts P275 are in engagement. Let it be further assumed that knife switches 260 and 261 are closed to connect the equipment to the source of supply and that safety control disabling knife switch 262 is closed to render \the safety control effective. The equipment within box 61 thereupon operates in the manner previously described with reference to Figure 5, and assuming the condition of the electrostatic field emanating from capacity device 50 to the normal, contacts 13122 of the door safety switch B are caused to separate.

The closing of knife switches 260 and 261 also results in the energization of the field 278 of the door motor 214, the field being connected directly across the lines 276 and 277.

The car operator, in starting the elevator car, first moves handle 270 to Close. A circuit is thereupon completed for the door closingswitch DC as follows: from the minus main, by way of knife switch 260, conductor 276, door close limit switch 227, actuating coil D0280, contacts T281 of the door opening sequence relay, contact 282, bridge 283 actuated by operator's handle 270, contact 284, conductor 277, knife switch 261, to the plus main. The resulting operation of the door closing switch causes the engagement of its contacts D0285 and D0287 and the separation of its contacts D0286. The separation of contacts DC286 renders the door opening switch D0 ineffective. The engagement of contacts D0287 completes a circuit for reset coil $288 of auxiliary car control relay S. Latch 290 for this relay is thereupon released, with the result that contacts S291 engage and contacts S292 and S293 separate. preparation for starting the elevator car. The functions of contacts S292 and $293 will appear as the description proceeds.

Resuming the description of operation of the door closing switch, the engagement of contacts D0285 completes a circuitfor releasing magnet 225 of the door operator brake- 224. This circuit is from conductor 276, by way of contacts D0285, contacts 0294 of the door control relay 0, brake release magnet 225, to conductor 277.

With door operator brake 224 released, the car and hatchway doors return to their closed position under the action of their respective closing springs. During such door closing operation, motor armature 295 is, in the embodiment of the The engagement of contacts S291 is ininvention illustrated in Figures '7, 8, 9 and 10, mechanically restored to its position corresponding to door closed position. Such restoration of armature 295 is subject to the dynamic braking action of motor 214, since motor field 278 is energized and dynamic brake resistance 301 is connected across armature 214 by means of contacts D0302. Since the speed with which the doors are closed cannot be greater than the speed with which motor armature 295 is restored to its position corresponding to door closed position, regulation of dynamic braking resistance 301 affords a control'of the closing speeds of the doors as well as of the restoration speed of armature 295.

Also during such door closing operation, the voltage induced across the terminals of motor armature 295 causes the energization of actuating coil U296 of the door motion switch U, contacts 250 of the shaft switch being in engagement. As a result, switch U operates to causethe engagement of its contacts U297 and U299 and the separation of its contacts U298 and U300. The engagement of contacts U297 is of no effect at this time. The function of contacts U298 and U300 willappear as the description proceeds. The engagement of contacts U299 completes an auxiliary circuit for dynamic braking resistance 301.

Concurrent with the movement of the car and hatchway doors from open position is the reengagement of the door open limit switch 226. Such action is of no result, however, inasmuch as contacts D0286 are then separated.

After the car and hatchway doors have moved a substantial portion of their total movement from open position, door actuated safety control disabling switch 247 is actuated by,c'ardoor 201 to cause theseparation of its contacts. The separation of these contacts renders inefiective any engagement of contacts B122 inasmuch as it breaks the circuit by which actuating coil 0303 of the door control relay may be energized. As a consequence, during the remaining portion of the closing operation of the doors, and while the doors are in closed position, all variations in the electrostatic field emanating from capacity device 50 which cause the engagement 'of contacts B122 are ineffective to control the doors. Thus, the change in the field of capacity device 50 resulting when the car door approaches the side post of the elevator car is ineffective to cause the operation of door control relay 0.

As the car and hatchway doors near fully closed position, the contacts of door close limit switch 227 are separated, thereby, resulting in the deenergization of actuating coil D0280. The resulting return of the door closing switch D0 to its initial position causes, by' the separation of its contacts D0285, the deenergi'zat ion of brake release magnet 225. The door operator brake 224 is thus applied. Incident to the resulting cessation of rotation of motor armature 295 is the return of door motion switch U to its initial deenergized position due to the failure of potential across the door motor armature. When the car and hatchway doors are in closed position, the car door and batch door interlock contacts 245 and 273, respectively, are caused to engage.

With the car and hatchway doors closed, let it be assumed that the operator in the car moves the handle 270 to Start". A circuit is thereby completed for actuating coil R304 of the car control relay. This circuit is from conductor 276, by way of contacts P275 of the up direction relay, car door and hatchway door interlock contacts 245 and 273 respectively, actuating coil R304, contacts S291, contact 305, bridge 283 controlled by handle 2'70, contact 284, to conductor 2'17. The resulting operation of the car control relay R causes the engagement of its contacts R264, R306 and R307 and the separation of contacts R263 and R308. The engagement of contacts R306 completes a holding circuit for actuating coil R304, this holding circuit being from contacts S291 direct to conductor 27? so that car control relay R is maintained in' actuated position regardless'of the subsequent positions of operators handle 270.

The engagement of contacts R264 efiects the starting of the elevator car in the direction determined by the actuated car direction relay, in this instance in the up direction. The elevator car is thus set in motion.

The separation of contacts R263 breaks the circuit by which the equipment within box 61, including the oscillator and rectifier tubes, are energized. As a consequence, while the car is in motion not only is the safety control equipment ineflective but such equipment is also deenergized.

The separation of contacts R308 is to insure that the door opening switch D0 cannot be energized while the car is in motion by moving operators handle 270 to Open.

The engagement of contacts R307 completes and maintains a circuit for actuating coil T310 of the door opening sequence relay. The func-- tion of the resulting separation of contacts T281 will appear as the description proceeds.

After the elevator car is set in motion, it is brought up to speed by means of equipment for simplicity not illustrated in Figure 10. Thereafter, the elevator car continues in motion until a stop is made at a floor in response to an actuated push button for such floor positioned either in the hall of such floor or in the car. Such stopping is eflected automatically by means of equipment for simplicity not illustrated in Figure 10. As an incident in each of such stops, contacts 274 are caused to engage momentarily as the car approaches the floor level for the floor .at which a stop is being made. The engagement of contacts 2'14 completes a circuit for actuating coil S311 of the auxiliary car control relay which, by its resulting operation, causes the engagement of contacts S292 and S293 and the separation 0! contacts S291. Latch 290 becomes efiective to maintain the contacts of the auxiliary car control relay S in the positions to which they have moved after contacts 274 separate.

The separation of contacts S291 breaks the holding circuit for actuating coil R304 of the car control relay. The engagement of contacts S292 completes the circuit for the actuating coil D0312 of the door opening switch. The engagement of contacts S293 is in preparation for the subsequent operation of the auxiliary car control relay S.

The return of the car control relay R to its initial position, resulting from the deenergization of actuating coil R304 by the separation of contacts S291, causes the engagement of contacts R263 and R308 and the separation of contacts'R264, R306 and R307. The engagement'of contacts R263 reenergizes the equipment, including the generator and rectifier tubes, within box 61, so that the safety control equipment within box 61 is restored to eflfectiveness. The separation of contacts R264 and R306 is in preparation for a subsequent startingof the elevator car. The function of contacts R308 will be described later.

The separation of contacts R307, in the event the operators handle 270 is in neutral, position, deenergizes actuating coil T310 of the door opening sequence relay so that contacts T281 reengage. In the event the operator's handle 2'70 is, at the time contacts R307 separate, in the Close or Start position so that there is a circuit from contact 282 to contact 284 by way of bridge 283, the separation of contacts R307 does not cause the dropping out of the door opening sequence relay T. This is due to the fact that a holding circuit exists for actuating coil T310 by way of resistance 313, contact 282, bridge 283 and contact 284. Contacts T281 of door opening sequence relay dering door closing switch DC inefiective, until the operators handle 270 is returned to neutral position. The object of this provision will appear as-the description proceeds.

The operation of door opening relay D0, resulting from the previously mentioned engagement of contacts S292 of the auxiliary car control relay S, causes the engagement of contacts are thus maintained separated, ren- D0314, D0315 and D0316 and the separation of contacts D0302. The engagement of contacts-.-'

D0314 completes a circuit for the brake release magnet 225, with the result that door operator brake 224 is released. The engagement of contacts D0315 and D0316 completes the circuit for energizing armature 295 of the door motor. Door motor 214 thereupon operates to cause the opening of the car and hatchway doors. The separation of contacts D0302 renders dynamic braking resistance 301 ineffective during door opening operation, contacts U299 being already disengaged when such door opening operation is started from fully closed position of the doors. The initial door opening operation of the door motor actuates shaft switch 248 to cause the separation of its contacts 250. As a result, door motion switch U is not actuated at any time during door opening operation, and contacts U297 and U299 remain separated, and contacts U298 and U300 remain engaged, during door opening operation.

As the car door leaves closed position, the contacts of door close limit switch 227 reengage in preparation for a subsequent door closing operation.

During door opening operation, contacts 247 of the door actuated safety control disabling switch are caused to engage so as to render eifective door control relay 0 and the contacts of door D0314 deenergizes brake release coil 225. The 5 resulting reengagement of contacts D0302 ren-' ders dynamic braking resistance 301 efiective. The door motor 214 is therefore brought to a'stop, the door operator brake 224 is applied, and the car and hatchway doors come to rest in their door open positions. 1

In the foregoing description it was assumed that no person or other body obstructed the closing of the be assumed that, while the car and hatchway doors are stationary in their fully open position, contacts 13122 are caused to engage as a result of a person or other body getting'into the electrostatic fleld produced in the elevator entranoeway by capacity device 50. A circuit is thercbrcompleted for actuating coil'C303 of the door control relay by way of contacts 247 of the door actuated safety control disabling switch, these contacts then being in engagement. The resulting operation of switch C causes the engagement of its contacts C317 and the separation of its contacts C294. The engagement of contacts C317 is of no eflect since contacts U297 of the door motion, switch are'then separated. The separation of contacts C294 is of no effect at the moment. However, in the event the operator moves the handle 270 to Close" or Start, thereby causing the actuation of door closing switch DC, the resulting engagement of contacts DC285 is rendered ineffective, by the separation of contacts D0294, to energize brake release magnet 225. Thus, so long as the person or other body remains in the electrosatic field produced in the elevator entranceway by capacity device and causes the engagement of contacts B122 while the doors are in open position, the door operator brake 224 cannot be released and the doors cannot be closed. when the person or'other body gets or is taken out of the electrostatic field and contacts B122 reseparate, door control'relay C is restored to its initial position with contacts C294 in engagement. The doors may then be closed in the normal manner.

Let it be assumed that, while the car and hatchway doors are in the process of closing, a person or other body gets in the electrostatic field produced in the elevator entranceway by the capacity device 50. It will be recalled that to eflect the closing of the car and hatchway doors operators handle 270 is in Close" or Start" position, actuating coil D0280 is energized and contacts DC285 are in engagement. It will also be recalled that during door closing operation contacts 250 of the shaft switch are in engagement,

actuating coil U296 is energized, contacts U297 are engaged and contacts U298 are separated. Thus, the presence of a person or other body in the field of capacity device 50 while the car and hatchway doors are closing, and the resulting engagement of contacts B122, completes a circuit for actuating coil C303 and causes the operation of the door control relay C. Contacts 0317 thereupon engage and contacts C294 separate.

The separation of contacts C294 deenergizes brake release coil 225 so that the door operator brake 224 is applied and the car and hatchwaydoors brought to a standstill. The engagement of contacts C317 causes a holding circuit for actuating coil C303 of the door control relay by way of contacts U297. Door control relay C is thus maintained in actuated position, even though the person or other body in the elevator entranceway gets or is taken out of the field of capacity device 50. As a consequence, even thoughcontacts B122 reseparate, door operator brake 224 remains effective to retard the closing motion of the car and hatchway doors, and to bring the doors to a standstill.

Retardation of the closing motion of the car and hatchway doors is assisted by the action of dynamic braking resistance 301, this resistance being eflective during door closing operation as a result of the engagement of contacts D0302 and also of the engagement of contacts U299.

when the car and hatchway doors are substantially stationary, the voltage induced in moengagement of contacts gized only in the event contacts B122 are in engagement. The car and hatchway doors are therefore maintained stationary in their partly closedpositions so long as a person or other body is in the electrostatic field in the elevator entranceway and causes the engagement of contacts B122. When such person or other body gets or is'taken out of the electrostatic field in the elevator entrancewayand contacts B122 reseparate, actuating coil C303 of the door control relay is thereupon deenergized. The resulting reengagement of contacts C294 recompletes the circuit for brake release magnet 225 (contacts DC285 are assumed to have remained in engagement) so that the door operator brake 224 is released. The car and hatchway doors therefore resume their closing operation and during the event the operator returns handle 270 to neutral positionso that door closing switch DC remained actuated. In the event the operator returns handle 270 to neutral position after the person .or other body in the elevator entranceway has initiated the operation of the safety control for automatically stopping the closing of the car and hatchway doors, such action on the part of the operator does not interfere with the completion of such automatic stopping of the doors. The only effect of such action is to cause the car and hatchway doors to remain stationary in partly closed position even after the person or other body has gotten or been taken out of the electrostatic held in the elevator entranceway. and contacts B122 have reseparated. This is due to-the separation of contacts D0285 incident to the return of operators handle 270 to neutral position. In the event the operator, after the passenger or other body in the elevator entranceway has initiated the operation of the safety control for automatically stopping the closing of the car and hatchway doors, moves handle 270 to "Open" position, such action also does not interfere with the completion of the automatic stopping of the doors. The movement of handle 270 to Open position causes bridge 283 to engage both contacts 320 and 321 so that a circuit is completed thereby for actuating coil D0312 of the door opening switch. The resulting operation of the door operating switch DO and the engagement of contacts D0314 is of no effect until the doors become substantially stationary, for while the doors, moving in closing direction, are brought to a standstill, door motion switch U is in actuated position with its contacts U298 and U300 separated. As a consequence, the engagement of contacts D0314 does not, while the doors are in the process of being brought to a standstill, complete a circuit for brake releasing magnet 225. Similarly, the engagement of contacts D0315 and D0316 door opening sequence relay. It will also be redoes not-result in energizing armature 295 of the door motor since contacts U300 are separated.

It is to be noted that the separation of contacts D0302, which is also incident to the operation of door opening switch DO, does not render dynamic breaking resistance 301 ineffective, since -contacts U299 are in engagement. The closing tacts U298 completes the circuit for brake release magnet 225 so that the door operator brake is thereupon released. The engagement of contacts U300 completes the energizing circuit for armature 295 of the door motor. The separation of contacts U299 renders dynamic braking resistance-301 ineffective. The door motor 214 is thereupon actuated to move the doors in door opening direction.

It is to be noted that during door opening operation, the presence of a person or other body in the electrostatic field of capacity device 50 does not influence the operation of the doors.

The door motor continues to move the doors toward open position as long as operators handle 270 is held in Open position. When operators handle 270 is restored to neutral position, door opening switch D0 is returned to its initial position, door motor 214 is deenergized and door operator brake 224 applied. In the event operators handle 270 is maintained in Open" position, the doors are brought to a stop by the separation of contacts 226 of the door open limit switch.

Movement of operator's handle 270 from Close or Start position to Open position while the doors are in the process of closing, results first in bringing the doors to a standstill by the application of door operator brake 224 and by the dynamic braking action of door motor 214. The door operator brake is applied as a result of the separation of contacts D0285 and is not released by the engagement of contacts D0314 until after the doors become substantially stationary and contacts U298 reengage. The dynamic braking action of door motor 214 continues while the doors are being brought to a standstill, notwithstanding the separation of contacts D0302, since dynamic braking resistance 301 is rendered effective by the engagement of contacts U299. After the doors become substantially stationary, door motion switch U drops back to its original position and the resulting reengagement of contacts U300 causes energization of door motor 214 to .move the doors in the opening direction, as previously described.

It was assumed in the early portion of the description of Figure 10 that up direction relay P.

was in actuated position with its contacts P275 in engagement. It is believed clear that the operations of the equipment herein described are the same when down direction relay Q is in actuated position with its contacts Q322 in engagement.

It will be recalled that, when the elevator car isstarted, the engagement of contacts R307 completes a circuit for actuating coil T310 of the called that, in the event operators handle 270 is in either Close or Start" position, the separation of contacts R807, incident to the, bringing of the elevator car to a stop, does not deenergize actuating coil T310. This is due to the fact that a holding circuit therefor exists by way of resistance 313, contacts 282, bridge 283 and contacts 284. The resultant continued separation of contacts T281 renders ineffective the door closing switch DC, thus insuring that contacts D0286 remain in engagement. Door opening relay DO thus becomes, and remains, effective. The energizing circuit for actuating coil D0312 completed by the engagement of contacts S292 as an incident to the stopping of the car, thus is not broken. The failure of the operator to return handle 270 to neutral during the stopping operation of the caras occasionally results from carelessness or inattention on the part ofthe operator-thus does not prevent the automatic opening of the car and hatchway doors. To reclose the doors, the operator must return the handle 2'70 to its initial position, thereby dropping out door opening sequence relay T, and then return handle 270 to Close or Start" position.

As with the embodiment of this invention illustrated in the wiring diagram of Figure 5, it is to be noted that in the event that any of the equipment within box 61 fails or becomes otherwise defective, contacts B122 engage and prevent closing of the doors. It is also to be noted that temporary operation of the doors without the safety control may be had by opening safety control disabling knife switch 262.

Shaft switch 248 is preferably operated by slow speed shaft 217 as illustrated, but if desired the switch may be operated by fast speed shaft In both of the illustrated embodiments of the invention, the contents of box 61 may, if desired, be positioned within trough member 51 of the capacity device 50.

It is to be understood that the invention is not limited to the particular circuit arrangements herein illustrated and described. Thus, if desired. the capacity device subject to the influence of a body in the elevator entranceway may control the frequency of the generator instead of controlling the tuned circuit of the detector, as in the illustrated embodiments. Alternatively, the capacity device may control both the frequency of the generator and the tuned circuit of the detector. Also, if desired, a plate may be mounted on or adjacent to the side post of the elevator car and electrically connected to the safety control equipment so as to serve as one of the plates of the electrostatic-field-creating device, the other of such plates being a plate similar to plate 53 mounted on the car door. In such event, trough member 51 may, if desired, be dispensed with.

It is also to be understood that the safety control equipment of this invention may be applied to door operators of types other than those herein shown and described.

It is to be observed that the amount of detuning necessary by the presence of a passenger or other object in the elevatorentranceway to cause the doors to stop or reverse when they are closing, is relatively small, and that this is subject to control by the design and adjustment of the safety control equipment. This sensitivity should be such that, when the doors are closing and a passenger or other object is in the path of the car door or the hatchway door or in the region between these doors, the doors are brought to a stop or reversed without having them hit or touch such passenger or other object.

Inasmuch as many changes could be made in the above constructions and' many apparent 1y widely different embodiments of 1 this invention could be made without departing from the scope thereof, it'is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In an elevator installation having an elevator car and an entranceway for providing access to said car; a door for said entranceway; power operated mechanism for moving said door to closed position; means creating an electrical field, in said entranceway; and'means responsive to the presence in said field of a body having an electrical characteristic which cooperates with said field to alter the same, for rendering said 'power operated mechanism ineffective to close said door. I

2. In an elevator installation having an elevator car and an entranceway for providing access to said car; a door for said entranceway; power operated mechanism for moving said door to closed position; means creating an electrical field in said entranceway; and means, effective during closing operation of said doonand responsive to the presence in said field of a body having an electrical characteristic which cooperates with said field to alter the same, for stopping said door before it strikes said body.

3. In an elevator installation;'two relatively movable bodies, one being the elevator hatchway and the other being the elevator car; a door on one of said bodies for afiording access to said car; power operated mechanism for closing said door; means including an element mounted on the other of said bodies for producing an electrical field extending over to said first body and in advance of said door during closing operation thereof; and means responsive, during closing operation of said door, to variations in said field due to the presence of a person or other body. in the path of said door, for rendering said power operated mechanism ineffective to close said door.

4. In an elevator installation; two relatively movable bodies, one being the elevator hatchway and the other being the elevator car; a door on one of said bodies for affording access to said car; power operated mechanism for closing said door; means mounted on the other of said bodies for producing an electrical field in which dispersion is a characteristic thereof so that, due to said dispersion, aportion of said field extends laterally over to said first body and in advance of said door during closing operation thereof; and means responsive, during closing operation of said door, to variations in said field due to the presence of a person or other body in the path or region of said door, for stopping closing movement of said door.

5. In an elevator installation; two relatively movable bodies, one being the elevator hatchway and the other being the elevator car; a door on one of said bodies for affording access to said car; power operated mechanism for closing said door;

means for producing an electrical'field in which ing motion of said door, and so that, due to said dispersion, a portion of said field extends laterally over to said first body and in advance of said door during closing operation thereof; and means responsive, during closing operation of said door, to variations in said field due to the presence of a person or other body in the path or region of said door, for rendering said power operated mechanism ineffective to close said door, and for stopping said door before it strikes said person or body in the event said door is in motion in the closing direction.

6. In an elevator installation having an elevator car and an entranceway for providing access to said car; a door for said entranceway; power operated mechanism for moving said door to closed position; means creating an electrostatic field in said entranceway; and means, effective during closing operation of said door and re* sponsive to the presence in said field of a body having the characteristic of alteringsaid field, for stopping said door beforevit strikes said body.

7. In an elevator installation; two relatively movable bodies, one being the elevator hatchway and the other being the elevator car; a door on one of said bodies for affording access to said car; power operated mechanism for closing said door; means mounted on the other of said bodies for producing an electrostatic field extending over to said first body and in advance of said door during closing operation thereof; and means responsive, during closing operation of said door, to variations in said field due to the presence of a person or other body in the path of said door, for rendering said power operated mechanism ineffective to close said door and for stopping said door before it strikes said person or body in the event ,said door is in motion in the closing direction.

8. In an elevator installation; two relatively movable bodies, one being the elevator hatchway and the other being the elevator car; a door on one of said bodies for affording access to said car; power operated mechanism for closing said door; an electrical capacity device mounted on-the other of said .bodies; means for impressing an alternating current voltage upon said capacity device, thereby producing an electrostatic field part of which, by dispersion, extends over to said first body and in advance of said door during closing operation thereof; and means responsive, during closing operation of said door, to variations in said field due to the presence of a person or other body in the path or region of said door; for stopping said door before it-strikes said person or body.

9. In an elevator installation having an elevator car serving a floor; a hatchway door at said floor; power operated mechanism for closing said hatchway door; means mounted on said car for creating an electrostatic field in the path of said hatchway door; and means responsive, d mi sing operation of said hatchway door, t v

both of said doors; means, including a'capa 1t 150, 1

device mounted on said car between the exterior 9s 10o Q 

